Matt, I don't know if you or Neil would consider playing solos as fitting under theory, but I think there is more to a good solo than imagination. Knowing where to be when chord changes are happening seems to fit this catagory.
Scott
Matt- I'm with Scott on this one. Neil has teased us a bit with Chord Soloing but the hardest thing about soloing isn't hitting the right notes in a scale pattern but putting them together to make something musical sounding. This could lead to blues, jazz, country, bluegrass, folk and rock soloing which all have slightly different styles and techniques.
Not sure this qualifies as theory but more practical application of theory.
:cheer: